Lifting device for a stand-up wheelchair, and a wheelchair using the same

ABSTRACT

A wheelchair having a lifting device wherein the seat and the footrest are independent from each other and are mounted on the top ends of two deformable quadrilaterals extending upwards from the chassis and sharing a common moving portion, and wherein the raising and lowering control devices comprise a drive member interposed between the chassis and one of the moving members of one of the quadrilaterals, and suitable for controlling the displacement of said quadrilaterals between a stable folded state and a stable unfolded state.

FIELD OF THE INVENTION

The present invention relates to wheelchairs used by handicapped personsand invalids and it applies equally well to folding and to non-foldingwheelchairs.

There is no doubt that wheelchairs have given mobility to handicappedpersons and invalids. However, such wheelchairs suffer from severaldrawbacks due to the fact that their users can occupy only a sittingposition, which position is generally maintained for relatively longperiods of time. In an attempt to remedy this single way of usingwheelchairs, various proposals have been made for "stand-up" wheelchairsenabling the user to be held substantially in a standing position.

PRIOR ART

As a general rule, the proposals made use a hinged structure comprisinga back, a seat, and a footrest. Such a structure is hinged, generallyvia the seat, about a front horizontal axis that is perpendicular to thevertical plane of symmetry of the chassis, and drive means areinterposed between the chassis and the structure to enable the structureto be raised or lowered, and thus to occupy a folded or "sitting"position or an unfolded or "standing" position. The drive member may becontrolled manually, electrically, or otherwise.

To illustrate that prior art, mention may be made of French patent69/35042, German application 2 625 045, or French patent 82/11713,amongst others.

Those various proposals do indeed satisfy the intended stand-upobjective, and in that sense they have undeniably provided improvedwell-being to users.

The structural proposals in the prior art rely generally on hinging thehinged structure about a horizontal front axis that is perpendicular tothe vertical plane of symmetry of the chassis and that is securedthereto.

In the stand-up position, that organization has the effect oftransferring the hinged structure and the stood-up user towards thefront of the wheelchair, thereby increasing the load on the front wheelsand reducing the load on the back wheels.

That gives rise to instability, since the support polygon is notuniformly loaded. That is why, as a general rule, additional supportpoints are provided to stabilize the wheelchair when the hingedstructure is in the stand-up state. Such additional support points arefrequently, if not always, constituted by castors, skids, props, or feetwhich are provided by construction to extend the footrest so as to bearon the ground when the hinged structure is in the stand-up state.

Although such a proposal, in the general sense, serves to provide agenuine factor of stability and safety for users, it nevertheless givesrise to a problem that is unavoidable when account is taken of thedesire for wheelchairs to be movable even when the hinged structure isin the stand-up state. That corresponds to the perfectly understandabledesire of users to be able to recover lifestyle and independence by suchmeans.

Reconciling such a desire with the present technique appears to beincompatible with achieving good stability and, where appropriate, easeof handling.

In an attempt to satisfy those two requirements, proposals have beenmade in the prior art for a different structure. Thus, e.g. asillustrated by patent U.S. Pat. No. 3,907,051, proposals have been madeto place motor-drive means in a box located at the back in order toballast the wheelchair so as to lower its center of gravity andcompensate for the front overload that occurs in the stand-up position.

Such a proposal must indeed provide a partial solution to problems ofstability and safety, but it does not appear to be usable in allconfigurations and with all kinds of energy that may be available forpowering a wheelchair.

Also, such a proposal appears to be difficult to make compatible withthe desire to have a wheelchair that is foldable to enable it to betransported easily, in particular in a motor vehicle.

In application WO 82/01314, the prior art has a different proposal whichconsists in mounting a hinged structure on the chassis of the wheelchairsuch that when the structure is moved into its stand-up position itmoves backwards relative to the chassis, thereby placing the structureand the user substantially on the vertical axis passing through thecenter of the support polygon constituted or defined by the chassis.

That ensures that the general load in the stand-up position isdistributed relative to the support polygon, thereby ensuring stabilityso that it is possible to envisage motorizing the wheelchair and movingit even in the stand-up position.

Nevertheless, on examining that proposal, it can be seen that thetechnology proposed in application WO 82/01314 is relatively complicatedand uses a large number of hinge points between the various elements ofthe hinged structure and numerous links connecting the structure to thechassis.

Such numerous hinge connections make the structure relatively fragile,increase overall weight, and require constant maintenance in order toprevent any local misfunction which would give rise to defective foldingor unfolding that could lead to accidents.

Also, a large fraction of the hinges are located near the front of thewheelchair, particularly in a zone in front of the seat, thus having theeffect of impeding access thereto for a handicapped person or invalid.

In addition, the fact of causing the hinged structure to move backwardsautomatically implies that the footrest must move in the same direction,from a front position corresponding to a sitting state to a backwardlyoffset position corresponding to a standing state.

This front-back displacement during both movements means that enoughclearance must be left for the footrest and poses a difficult-to-solveproblem in fitting the swivel-mounted front wheels to the chassis, whichwheels are generally of smaller diameter than the load-carrying backwheels, as is usually the case for wheelchairs.

This constraint complicates manufacture of the wheelchair, and makes itdifficult for the size of the wheelchair, particularly its transversesize, to be kept compatible with the clearance available in use,particularly in the home, where it must be possible for the wheelchairto pass through doorframes of standard size.

The number of hinges and the large number of links also have the effectof adding considerable weight to the wheelchair equipped therewith, thusmaking it more difficult to handle while also requiring the user toexpand more physical force when wheelchair displacement is not poweredor power-assisted by on-board motorization.

The present invention seeks to remedy the above drawbacks by proposingnovel connection means between a hinged structure and a chassis of astand-up wheelchair, with such means not only making standing uppossible, but also serving automatically and simultaneously with thestanding-up operation to move the hinged structure backwards so as tocause the load in the standing position to be centered relative to thesupport polygon, thereby imparting sufficient stability and safety tothe wheelchair in such a state for it to be mobile, with an option ofbeing displaced manually or by motor means, and without any risk for thesubject in the standing position.

Another object of the invention is to provide support and hinge meansthat are simple, reliable, light in weight, and cheap, so as to makethem easy to fit, without thereby greatly increasing the weight of thewheelchair, and also making it possible, where appropriate, to fit themon folding wheelchairs.

SUMMARY OF THE INVENTION

To achieve the above objects, in the lifting device for a stand-upwheelchair of the invention:

the seat and the footrest are independent from each other and aremounted on the top ends of two deformable quadrilaterals extendingupwards from the chassis and possessing a moving portion in common; and

the means for controlling raising and lowering comprise a drive memberinterposed between the chassis and one of the moving members of one ofthe quadrilaterals, and suitable for causing said quadrilaterals to movebetween a stable, folded state corresponding to a "sitting" position forthe structure and a stable, unfolded state corresponding to a "standing"position for the structure in which the mass represented by thestructure is substantially centered relative to the support polygon.

The invention also provides a stand-up wheelchair including a hingedstructure connected to the chassis by the above means.

Various other characteristics appear from the following descriptiongiven with reference to the accompanying drawings which show embodimentsof the invention as non-limiting examples.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic side elevation of a wheelchair of theinvention.

FIG. 2 is a front view as seen on line II--II of FIG. 1.

FIGS. 3 and 4 are views analogous to FIG. 1, showing the wheelchair intwo characteristic positions.

FIG. 5 is a front view analogous to FIG. 2, but showing a variantembodiment.

BEST MANNER OF FORMING THE INVENTION

FIGS. 1 and 2 are a diagram showing a wheelchair 1 having a chassis 2constituted by a bottom frame 3, e.g. comprising longitudinal beams 4interconnected by tranverse or lateral cross bars 5 and 6. Naturallythis embodiment is given merely by way of example and is showndiagrammatically solely for the purpose of avoiding excessive clutter inthe drawing while enabling the invention to be understood. Thus, inconventional known manner, the chassis 2 is provided with wheels 7 thatare generally load-carrying, main, and motor-driven, and wheels 8 thatare castor-mounted and swivel from pivots 9. The wheels 8 are usually,but not necessary, placed at the front of the chassis 2, while theload-carrying wheels 7 are at the back thereof. Via their points ofcontact with the ground S, the wheels 7 and 8 define a support polygonhaving a vertical axis x--x' passing through the center thereof. Thewheels 7 are mounted on the chassis 2 via bearings 10 and they mayadvantageously be associated with reversible motor drive means 11 suchas electric motors suitable for being powered from an on-boardelectricity source 12 disposed on a bracket 13 placed between uprights14.

In conventional manner, the chassis 2 supports a hinged structurecomprising a seat 20, a back 21, and a footrest 22. In known manner thehinged structure is organized to be capable of occupying a stable,folded state corresponding to a "sitting" position, as shown in FIG. 1,and also a stable, unfolded position corresponding to a "standing"position, as shown in FIG. 4 wherein the seat, back and foot rest are ingeneral upright alignment. In both of these positions the hingedstructure is equipped to support a handicapped person or invalid in asitting position or in a standing position, as the case may be, by usingmeans known in the art and not shown.

In the invention, the hinged structure is organized so that the seat 20is carried by the chassis 2 via hinge means 23 in the form of adeformable quadrilateral, such means being organized, for example, inthe form of two lateral linkages 24. Each lateral linkage comprises aback hinged portion or link 25 and a front hinged portion or link 26which are respectively mounted via axes 27 and 28 on the back upright 14and on the beams 4. The top ends of the hinged portions or links 25 or26 carry the seat 28 via respective hinge axes 29 and 30 respectivelylocated substantially in the middle portion of the bottom face of theseat 20 and at the front thereof. In the folded state, the portion 25extends forwards in a substantially horizontal direction from theuprights 14, whereas the front hinged portion 26 also extends forwardsbut with a rising inclination from the chassis 2.

In the invention, the back 21 is mounted via a hinge axis 31 on the backportion of the seat 20 and it is connected thereto via hinge means 32 inthe form of a deformable quadrilateral. The means 32 include a movingportion which is in common with the deformable quadrilateral 23.

By way of example, the means 32 may be constituted by an extension 21aextending downwards from the back 21 and on which a moving portion 34such as one or two links is hinged about an axis 33, the link(s) beingconnected about an axis 35 to the back link portion(s) 25 constitutingthe deformable quadrilateral 23 the third deformable quadrilateral thuscomprises a link 34 connected to linkage 25 of the first deformablequadrilateral; a link of linkage 25 between connectors 35 and 29; a linkof the seat between connections 29 and 31; and the extension 21a.

The moving portion 34 may also be organized as two lateral linkages inthe same manner as the linkages 24.

The footrest 22 is preferably constituted by two leg-pieces 40 eachprovided at its bottom end with a sole flap 41. The two leg-pieces 40are independent and they are not hinged to the seat 20, instead they arecarried by the chassis 2 via hinge means 42 preferably of the deformablequadrilateral type and organized like the other quadrilaterals in theform of two lateral linkages. Each lateral linkage comprises a frontportion 43 hinged about an axis 44 to the chassis 2 and carrying thecorresponding leg-piece via a top hinge axis 45. Each lateral linkagealso makes use of an element in common with the deformable quadrilateral23 as so to make up a deformable quadrilateral, with the common elementbeing constituted by the front portion 26 which, under suchcircumstances, is situated behind the front portion 42. To make thispossible, the front portion 26 is provided, beneath its hinge connection30 to the seat 20, with an extension 46 on which the leg-piece 40 ismounted via a hinge axis 47.

The front portion 43 of each deformable quadrilateral 42 extendsforwards with a rising slope from the chassis 2 to the leg-piece 40.

As can be seen in FIG. 1, the deformable quadrilateral system 23 isdefined by hinge points 27, 28, 29, and 30. The deformable quadrilateralhinge system 32 is defined by hinge points 29, 31, 33, and 35. The hingesystem 42 based on a deformable quadrilateral is defined by hinge points28, 44, 45, and 47.

In the invention, provision is made for the lifting device describedabove to be provided with a drive member 50 enabling the hingedstructure to go from its position shown in FIG. 1 to its position shownin FIG. 4, and back again. Such a drive member 50 may be constituted bya manually controlled mechanism, or preferably by an energy-transformingmechanism of the electrical actuator type that is suitable for beingpowered from the electricity source 12, in particular via a controlswitch 51 that is accessibly-located, e.g. on one of the removable orfoldable arms 52 fitted to the back 21 or to the seat 20. The drivemember 50 is interposed between the chassis 2 and one of the movingelements of one of the deformable quadrilaterals, and preferably theelement 25 connected to the seat 20. In an appropriate example as shownin FIG. 1, the drive member 50 is constituted by an electrical actuatorwhose base is fitted to the chassis 2 and whose rod is hinged, forexample, about an axis 53 of a cross-member interconnecting the portions25 of the two lateral linkages 24.

When a drive member 50 is used that is manually-driven, provision may bemade for resilient compensation means such as gas actuators that serveto reduce the load, particularly while the hinged structure is beingunfolded from its state shown in FIG. 1 to the stand-up state shown inFIG. 4.

Although not shown, the chassis 2 may be designed to have one or moreabutments 60 for holding the hinged structure in its folded state, e.g.by co-operating directly or indirectly with the seat 20 and/or with anappropriate one of the deformable quadrilaterals.

In the state shown in FIG. 1, the hinged structure is in its foldedposition such that the seat 20 is substantially horizontal and thefootrest 22 lies immediately in front of the front portion of thechassis and the transverse plane of the swivel pivots for the castors B.

When it is desired to cause the hinged structure to change state so asto occupy a stand-up position, the drive member 50 is actuated, e.g. toextend its rod, thereby raising the hinged elements 25 forming parts ofthe deformable quadrilaterals 23 associated with the seat 20. The hingedelements 25 are thus caused to pivot in the direction of arrow f₁ (FIG.3) about the axes 27, thereby displacing the axis 29 along a circulartrajectory T₁ whose center is the axis 27 and whose radius is the lengthof the elements 25.

Displacement of the axis 29 entrains the seat 20 in the same directionso that its hinge axis 30 is displaced along a circular trajectory T₂whose center is the axis 28 and whose radius is the length of the frontportion 26. The structural characteristics of the deformablequadrilateral 23 are such that the curves T₁ and T₂ intersect at a pointO₁ (as shown in FIG. 3) so that the seat being displaced backwards issimultaneously subjected to relative pivoting in the direction of arrowf₂.

Simultaneously, the pivoting of the seat 20 causes the axis 31 to bemoved upwards, thereby subjecting the back 21 to displacement relativeto the seat although continuing to remain at substantially the sameinclination. This characteristics is provided by the structure ofdeformable quadrilateral 32.

The displacement of the point 30 along the curve T₂ causes hinge point47 of deformable quadrilateral 42 to move along curve T₃, with thetrajectory T₃ having hinge point 28 as its center and having a radiuscorresponding to the portion of the link 26 that extends between saidpoint and the axis 47. Via the leg-pieces 40, the hinge points 45 aredisplaced along a circular trajectory T₄ whose center is the axis 44 andwhose radius is the length of the front elements 42.

This characteristic ensures that during the intermediate stage thatcoincides with displacement of the seat 20 along arrow f₂, the footrest22 is raised and displaced backwards, as can be seen in FIG. 3. Theamount of lifting is determined by the structural characteristics of thedeformable quadrilateral 42 such that when the sole flaps 41 lie abovethe horizontal pivoting envelope of the front wheels 8 with theirinitial inclination, they are situated at a height above the ground Sthat is greater than the diameter of the wheels. This ensures that thefootrest 22 can be moved backwards freely whatever the position in whichthe swivelling front wheels 8 are pointing.

The characteristics of the deformable quadrilaterals are selected byconstruction so that once the drive member 50 has moved along its activestroke, the seat 20 and the back 21 are located substantially inalignment at a small inclination, whereas the footrest 22 is movedbackwards to be included within the support polygon defined by thewheels 7 and 8. In this "stand-up" state, and as can be seen in FIG. 4,the hinged structure is distributed overall on either side of thevertical axis x--x' so that the load or mass that it represents on itsown plus that constituted by the subject in the standing position lieson said vertical axis x--x' and substantially in the center of thesupport polygon so as to ensure that the wheelchair, once put into thisconfiguration, is in a stable state enabling it to be displaced by meansof its wheels.

The structural characteristic of the support means and of the hingesystem based on three deformable quadrilaterals is such as to cause theback, the seat, and the footrest to move along trajectories T₁, T₂, T₃,and T₄ which extend towards the back portion of the wheelchair, therebydisplacing the hinged structure backwards so as to bring it from asomewhat forward sitting position towards a standing position that issubstantially cantered on the axis x--x'.

As can be seen by comparing FIGS. 1, 3, and 4, the means of theinvention make it possible in the standing position to reduce bulkconsiderably in the front-back plane of the wheelchair, and to impart acompact configuration to the wheelchair in this state that is favorableto moving about.

Operation in reverse to that described above takes place when the member50 is caused to return the hinged structure from its stand-up positionto the sitting position shown in FIG. 1.

FIG. 5 shows a variant embodiment in which the deformable quadrilateralsare no longer organized as lateral linkages such as 24, but in the formof a column, being brought together on either side of the front-backvertical plane of symmetry P--P'.

INDUSTRIAL APPLICATION

Particularly advantageous industrial application for the invention liesin stand-up wheelchairs which, are also capable of being folded about alongitudinal vertical plane of symmetry so as to take up less spacewhile being transported, particularly by car.

The invention is not limited to the examples described and shown sincevarious modifications can be applied thereto without going beyond theambit of the invention.

I claim:
 1. A lift device mounted to a wheelchair including a chassisextending longitudinally and transversely relative to the wheelchair,wheels carried by the chassis defining a support polygon, the chassisalso supporting hinged structures including at least a seat, a leg piececarrying a foot rest and a back rest, said seat, leg piece and back resteach being movable between a folded sitting position and an unfoldedstanding position, wherein the lift device comprises:a firstquadrilateral device comprising a first pair of linkages having opposedends extending between the chassis and the seat, each linkage pivotallyconnected at a first end to the seat and at a second end to the chassis,the connections between said first ends and the seat and between saidsecond ends and the chassis being longitudinally spaced apart along theseat and chassis, respectively; a second quadrilateral device comprisinga second pair of linkages each having opposed ends connectedrespectively to the leg piece at first ends thereof and to the chassisat second ends thereof, said connections between said first ends and theleg piece and between the second ends and the chassis beinglongitudinally spaced apart along the leg piece and chassis,respectively; said first and second quadrilateral devices sharing acommon linkage and said leg piece being supported by the secondquadrilateral device for motion that is independent of the motion of theseat; a device for moving at least one linkage of the quadrilateraldevices pivotally about an end of the one linkage connected to thechassis to move the quadrilateral devices, the seat and the leg piecesimultaneously between folded and unfolded positions relative to thechassis; said seat and foot rest at said unfolded position being locatedin general upright alignment within the support polygon.
 2. A liftdevice according to claim 1, wherein the motion of the connectionsbetween said first ends of said linkages of said first quadrilateraldevice and said seat solely determine the motion of said seat, said seatnot otherwise being connected to the chassis during pivotal motion ofsaid linkages of said first quadrilateral device.
 3. A lift deviceaccording to claim 1, said seat including a longitudinally rearwardportion and said back rest including a base section pivotally connectedto the rearward portion of the seat, and further comprising:a thirdquadrilateral device comprising: a link between said back rest and alinkage of said first quadrilateral device; a length of saidlast-recited linkage of said first quadrilateral device; a length of theseat between the connection of the last-recited linkage of the firstquadrilateral device to the seat and the connection between the backrest base section and the seat; and a back rest extension extendingbetween the back rest and said link extending between the back rest andsaid last-recited linkage of the first quadrilateral device.
 4. A liftdevice according to claim 1, wherein said first and second pairs oflinkages of said first and second quadrilateral devices are eachconstituted of laterally spaced pairs of linkages connected between theseat and chassis in the manner recited with respect to said first andsecond pairs of linkages.
 5. A lift device according to claim 1, whereinsaid linkages of said first and second quadrilateral devices are locatedadjacent to each other centrally between the wheels and below the seatwhen the seat is in the folded position.
 6. A lift device according toclaim 1, wherein the wheel chair chassis includes a lower portion and araised rear portion located above the lower portion, and wherein one ofsaid pair of linkages of said first quadrilateral device extends from aforward area of the seat to the lower portion of the chassis and theother of said pair of linkages of said first quadrilateral deviceextends from a longitudinal middle area of the seat and the raised rearportion of the chassis.
 7. The lift device according to claim 1, whereinthe chassis includes a lower portion and said leg piece includes forwardand rear portions; and wherein said common linkage extends from thelower portion of the chassis to the rear portion of the leg piece andthe other of the pair of linkages of said second quadrilateral deviceextends from the lower portion of the chassis to the forward portion ofthe leg piece.
 8. A lift device according to claim 1, wherein saiddevice for moving at least one linkage is an energy transformer.
 9. Alift device according to claim 1, wherein said device for moving atleast one linkage is a manual drive device and including a resilientload reducing compensator arrangement to assist the manual device forunfolding the seat, leg piece and back rest.
 10. A lift device mountedto a wheelchair including a chassis extending longitudinally andtransversely relative to the wheelchair, wheels carried by the chassisdefining a support polygon, the chassis also supporting hingedstructures including at least a seat, a leg piece carrying a foot restand a back rest, said seat, leg piece and back rest being movablebetween a folded sitting position and an unfolded standing position,wherein the lift device comprises:a first quadrilateral devicecomprising a first pair of linkages having opposed ends extendingbetween the chassis and the seat, each linkage pivotally connected at afirst end to the seat and at a second end to the chassis, theconnections between said first ends and the seat and between said secondends and the chassis being longitudinally spaced apart along the seatand chassis, respectively; a second quadrilateral device comprising asecond pair of linkages each having opposed ends connected respectivelyto the leg piece at first ends thereof and to the chassis at second endsthereof, said connections between said first ends and the leg piece andbetween the second ends and the chassis being longitudinally spacedapart along the leg piece and chassis, respectively; said first andsecond quadrilateral devices sharing a common linkage; a device formoving at least one linkage of the quadrilateral devices pivotally aboutan end of the one linkage connected to the chassis to move thequadrilateral devices, the seat and the leg piece simultaneously betweenfolded and unfolded positions relative to the chassis; said seat andfoot rest at said unfolded position being located in general uprightalignment within the support polygon; said seat including alongitudinally rearward portion and said back rest including a basesection connected to the rearward portion of the seat; a thirdquadrilateral device comprising: a link between said back rest and alinkage of said first quadrilateral device; a length of saidlast-recited linkage of said first quadrilateral device; a length of theseat between the connection of the last-recited linkage of the firstquadrilateral device to the seat and the connection between the backrest base section and the seat; and a back rest extension extendingbetween the backrest and said link extending between the back rest andsaid last-recited linkage of the first quadrilateral device.
 11. A liftdevice according to claim 10, wherein the motion of the connectionsbetween said first ends of said linkages of said first quadrilateraldevice and said seat solely determine the motion of said seat, said seatnot otherwise being connected to the chassis during pivotal motion ofsaid linkages of said first quadrilateral device.
 12. A lift deviceaccording to claim 11, wherein said leg piece is supported by the secondquadrilateral device for motion in folding and unfolding directions thatis independent of the motion of the seat in folding and unfoldingdirections.